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' (No Model.)

R. M.FRYER,

SCREW PROPELLBR.

Patented Aug. 14, 1883.

INVENTOR N PETERS. Phuko-Lllhagn'phr. Wampum D. C.

UNITED, STATES PATENT rrrcn.

ROBERT M. FRYER, OF NEW YORK, N. Y., ASSIGNOR TO GEORGE D. LEONARD AND IDA J. FRYER, OF SAME PLACE.

SCREW-PROPELLER.

SPECIFICATION forming part of Letters Patent No; 283,336, dated August 14:, 1883.

- Application filed November 15, 1882. (N0 model.)

To all whom it may concern.-

Be it known that I, ROBERT M. FRYER, of the city, county, and State of New York, have invented certain new and useful Improvements in Screw-Propellers, as fully described hereinafter.

The object of my invention is to increase the efficiency of the screw-propeller by preventing as far as possible the slips due to the breaking up of the water, and to enable the different blades to act successively upon the same water with propulsive effect; and this I accomplish by arranging the blades spirally around a shaft or hub, giving to each succeeding blade in the series an increased pitch. The spiral arrangement of the blades upon the shaft affords a space between each two blades for the passage of water, which permits the f screw more readily to clear itself of broken one by reason of the movement of the water.

In order, therefore, toequalize the action of the blades, it becomes necessary to increase the pitch so as to preserve the same relative angle between the water and the working-surfaceof the succeeding blades.

Referring to the accompanying drawings, Figure I is a side elevation of a screw constructed according to my plan, and showing Fig. 2

hub upon which the blades pitch than A, and O has a greater pitch than B, and so on to the end of the series. Any number of blades may be used, although four or six will probably be found in practice to be the most advantageous number.

I am aware that a spiral arrangement of the blades of a propeller upon their shaft is not new, and I am also aware that continuous screws with increasing pitch have before been made; but I am not aware that separate blades have ever been arrangedspirally and with increas ing pitch.

I am also aware that a plurality of propeller-wheels or a series of blades or floats have been used,-0ne ahead of the other, each propeller-wheel or series of blades toward the stern being provided with greater pitch than the preceding wheel or series; but 7 What I claim as my invention, and desire to secure by Letters Patent, is-

A screw-propeller consisting of a hub provided with blades or flanges in spiral order, so asto produce for each bladeor flange a separate line of rotation, each blade or flange in one direction having an increased pitch as compared with the preceding blade or flange, substantially as and for the purposes set forth.

ROBT. M. FRYER. 

